following strenuous exercise. Determine the empirical formula of lactic acid given that combustion of a 10.0-g sample produces 14.7 g CO2 and 6.00 g H2O. Ascorbic acid (vitamin C) contains C, H, and O. In one analysis, combustion of 5.24 g of ascorbic acid yields 7.86 g CO2 and 2.14 g H2O. Calculate the empirical formula and molecular formula of ascorbic acid given that its molar mass is about 176 g.